參數(shù)資料
型號： MAX802M
廠商： Maxim Integrated Products, Inc.
英文描述： Microprocessor Supervisory Circuits(具有看門狗和支持備用電池,高精度復位器)
中文描述： 微處理器監(jiān)控電路
文件頁數(shù)： 6/12頁
文件大?。?/td> 122K
代理商： MAX802M
M
_______________Detailed Desc ription
Reset Output
A microprocessor’s (μP’s) reset input starts the μP in a
known state. When the μP is in an unknown state, it should
be held in reset. The MAX690A/MAX692A/MAX802L/
MAX802M assert reset during power-up and prevent code
execution errors during power-down or brownout condi-
tions.
On power-up, once V
reaches 1V,
RESET
is guaran-
teed to be a logic low. As V
rises,
RESET
remains
low. When V
CC
exceeds the reset threshold, an internal
timer keeps
RESET
low for a time equal to the reset
pulse width; after this interval,
RESET
goes high (Figure
2). If a brownout condition occurs (if V
dips below
the reset threshold),
RESET
is triggered. Each time
RESET
is triggered, it stays low for the reset pulse width
interval. Any time V
goes below the reset threshold,
the internal timer restarts the pulse. If a brownout con-
dition interrupts a previously initiated reset pulse, the
reset pulse continues for another 200ms. On power-
down, once V
goes below the threshold,
RESET
is
guaranteed to be logic low until V
CC
droops below 1V.
RESET
is also triggered by a watchdog timeout. If a
high or low is continuously applied to the WDI pin for
1.6sec,
RESET
pulses low. As long as
RESET
is assert-
ed, the watchdog timer remains clear. When
RESET
comes high, the watchdog resumes timing and must be
serviced within 1.6sec. If WDI is tied high or low, a
RESET
pulse is triggered every 1.8sec (t
WD
plus t
RS
).
The MAX805L active-high RESET output is the inverse
of the MAX690A/MAX692A/MAX802L/MAX802M
RESET
output, and is guaranteed to be valid with V
down to
1.1V. Some μPs, such as Intel’s 80C51, require an
active-high reset pulse.
Watc hdog Input
The watchdog circuit monitors the μP’s activity. If the
μP does not toggle the watchdog input (WDI) within
1.6sec, a reset pulse is triggered. The internal 1.6sec
timer is cleared by either a reset pulse or by open cir-
cuiting the WDI input. As long as reset is asserted or
the WDI input is open circuited, the timer remains
cleared and does not count. As soon as reset is
released or WDI is driven high or low, the timer starts
counting. It can detect pulses as short as 50ns.
Power-Fail Comparator
The PFI input is compared to an internal 1.25V refer-
ence. If PFI is less than 1.25V,
PFO
goes low. The
power-fail comparator is intended for use as an under-
voltage detector to signal a failing power supply; it
Mic roproc essor S upervisory Circ uits
6
_______________________________________________________________________________________
1.25V
0.8V
WATCHDOG
TIMER
PFO
RESET
(RESET)
V
OUT
RESET
GENERATOR
BATTERY-SWITCHOVER
CIRCUITRY
1.25V
3.5V
V
BATT
V
CC
PFI
WDI
MAX690A
MAX692A
MAX802L
MAX802M
MAX805L
( ) ARE FOR MAX805L ONLY.
GND
Figure 1. Block Diagram
t
RS
+5V
0V
V
CC
0V
+5V
0V
+5V
RESET
0V
(RESET)
3.0V
3.0V
V
OUT
+5V
0V
PFO
V
BATT
= PFI = 3.0V
I
OUT
= 0mA
( ) ARE FOR MAX805L ONLY.
Figure 2. Timing Diagram
相關(guān)PDF資料
PDF描述
MAX690A Microprocessor Supervisory Circuits(帶看門狗和電池開關(guān)的復位器,復位門限4.65V)
MAX692A Microprocessor Supervisory Circuits(帶看門狗和電池開關(guān)復位器,復位閾值4.40V)
MAX8069 Low-Voltage Reference
MAX8069ESA Low-Voltage Reference
MAX8069CCZQ Low-Voltage Reference
相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
MAX802MCPA 功能描述:監(jiān)控電路 RoHS:否 制造商:STMicroelectronics 監(jiān)測電壓數(shù): 監(jiān)測電壓: 欠電壓閾值: 過電壓閾值: 輸出類型:Active Low, Open Drain 人工復位:Resettable 監(jiān)視器:No Watchdog 電池備用開關(guān):No Backup 上電復位延遲（典型值）:10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel
MAX802MCPA+ 功能描述:監(jiān)控電路 MPU Supervisor RoHS:否 制造商:STMicroelectronics 監(jiān)測電壓數(shù): 監(jiān)測電壓: 欠電壓閾值: 過電壓閾值: 輸出類型:Active Low, Open Drain 人工復位:Resettable 監(jiān)視器:No Watchdog 電池備用開關(guān):No Backup 上電復位延遲（典型值）:10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel
MAX802MCSA 功能描述:監(jiān)控電路 RoHS:否 制造商:STMicroelectronics 監(jiān)測電壓數(shù): 監(jiān)測電壓: 欠電壓閾值: 過電壓閾值: 輸出類型:Active Low, Open Drain 人工復位:Resettable 監(jiān)視器:No Watchdog 電池備用開關(guān):No Backup 上電復位延遲（典型值）:10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel
MAX802MCSA+ 功能描述:監(jiān)控電路 MPU Supervisor RoHS:否 制造商:STMicroelectronics 監(jiān)測電壓數(shù): 監(jiān)測電壓: 欠電壓閾值: 過電壓閾值: 輸出類型:Active Low, Open Drain 人工復位:Resettable 監(jiān)視器:No Watchdog 電池備用開關(guān):No Backup 上電復位延遲（典型值）:10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel
MAX802MCSA+T 功能描述:監(jiān)控電路 MPU Supervisor RoHS:否 制造商:STMicroelectronics 監(jiān)測電壓數(shù): 監(jiān)測電壓: 欠電壓閾值: 過電壓閾值: 輸出類型:Active Low, Open Drain 人工復位:Resettable 監(jiān)視器:No Watchdog 電池備用開關(guān):No Backup 上電復位延遲（典型值）:10 s 電源電壓-最大:5.5 V 最大工作溫度:+ 85 C 安裝風格:SMD/SMT 封裝 / 箱體:UDFN-6 封裝:Reel
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